A WW1 soldier out in the open? Must have been really early 1914 or late 1918. Judging by the helmet and uniform, probably the latter. Or it’s just propaganda material.
It's interesting that ultimately everything they tried, failed. The tank is about the only thing to come out of WW1, outside of aviation of course. Infantry is still just running around in regular clothes, shooting guns at each other. All of the experimental stuff couldn't hold up to the realities and horrors of war. At least they gave up on trench warfare, although that might see a comeback if the major powers are ever fighting over 2' of land at a time again.
I mean, helmets and body armor were eventually widely adopted, as were infiltration tactics and both light machine guns and submachineguns. They just had far more failures than they had successes.